Hi,
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The midcycle bleeding/spotting could be due to hormonal contraceptive use, pregnancy, ovulation bleeding, hormonal imbalances etc. The exact cause can only be made out after careful examination and investigations. Wait and watch for your test results and periods. Consider using additional protection when having intercourse while you are on any other medications (especially antibiotics) as they can affect efficacy of your birth control and put you at risk for pregnancy. Be in regular follow-up with your treating doctor/gynecologist.
Take care.